Many vasocclusive events, such as heart attacks and strokes, are caused by plaque build-ups in arteries. As one specific example, atherosclerotic plaque is known to build-up in the walls of arteries in the human body. Such plaque build-up restricts circulation and often causes cardiovascular problems, especially when the build-up occurs in coronary arteries.
One common method for opening partially occluded body internal passages is to guide a medical device to the diseased site, where it is used to carry out the needed treatment. A guidewire is usually used for advancing a catheter device thereover via body internal passages towards the treatment site. Typically, the distal tip of the guidewire is introduced into the body of the treated subject via an incision and advanced therethrough towards the treatment site, thereby forming a path leading to the occluded site through said body internal passages. The catheter, or any other suitable treatment devices (e.g., balloon catheter, stent or rotational atherectomy device), may be then threaded over the guidewire and advanced through said internal passages using the guidewire as a rail.
Total or near-total occlusions in body internal passages can, partially or entirely, block the passage therethrough. For example, in patients who suffer from coronary CTO (chronic total occlusion), the successful performance of a Percutaneous Transluminal Coronary Angioplasty (PTCA) is a technical challenge. The factor that is most determinative of whether the practitioner can successfully perform PTCA on patients suffering from coronary CTO is his ability (or inability) to advance a suitable guidewire from a position proximal of the lesion to a position distal of the lesion while remaining inside the true vessel lumen (without performing perforation or dissection of the artery wall).
In some instances, such as where the occlusive matter is soft or where the body internal passage is partially occluded, the guidewire can easily be pushed through the occlusive matter itself, thereby allowing the guidewire to remain within the body internal passage. However, in other cases, such as when the body internal passage is totally occluded by hard plaque (e.g., calcified atherosclerotic plaque), the guidewire cannot cross the occlusion and may deviate to the side and penetrate through layers of the passage walls (e.g., the intima—inner layer of a vessel wall), thereby creating a neo-lumen therethrough (e.g., through the sub-intimal space—within the wall of the artery between the intima and media, or adventitia i.e. a dissection), or even completely exit said internal passage i.e. a perforation.
Several techniques are known for passing through an occluded internal passage, such as laser catheters (U.S. Pat. No. 6,673,064), ultra sonic catheters (U.S. Pat. No. 6,702,748), and tissue displacement or hinged expansion devices (U.S. Pat. No. 6,800,085). In all of those techniques the occlusion is opened by means of a catheter device equipped with operative means for occlusions opening. However, the prior art devices suffer from lack of flexibility and maneuverability due to the bulky structure of their catheter devices. Consequently, the treatment procedures which utilize these prior art devices are substantially different from conventional catheterization procedure workflow as commonly practiced in regular cases (non CTO cases).
The aforementioned prior art solutions also suffer from lack of ability to indicate to the practitioner in real time, i.e. while carrying out the procedure, whether he is navigating the treatment devices through the occlusion (true lumen) or if he is actually perforating or dissecting the body internal passage, e.g. the artery.
Other known procedures, such as described in U.S. Pat. No. 6,852,109, propose a method for forming a passage through the CTO by a guidewire having active Radio Frequency (RF) ablation tip, with Optical Coherence Reflectometry (OCR) capability for sensing the position of the tip. However this known type of guidewire is a special guidewire comprising a mechanism for transferring RF energy and a following catheter with fiber optics for the OCR capability. These restraints are relatively rigid and therefore diminish the flexibility of the device, which is an important feature for carrying out in vivo navigation. Thus, also this prior art device suffers from lack of flexibility, and the need to deviate from the conventional practice workflow of the practitioner.
Another solution used for determining whether an organic tissue is healthy or not is using IVUS (intravascular ultrasound), for example as described in U.S. Pat. Nos. 6,685,644 and 6,685,643, however lack of data due to poor transmission in this known method and calcified build-ups that cause “acoustic shadowing” yield poor results in determining tissue type and true lumen detection.
In still another solution used such as described in U.S. Pat. No. 5,908,395, a hand held vibrator is attached to the proximal side of a guide wire, or a catheter through which the guidewire is threaded.
The guidewire then conveys the proximal vibrations to its distal end, subject to the specific passage of the guidewire thru the arteries. If indeed these vibrations reach the distal end of the guidewire they may be efficient in penetrating and recanalization of CTOs (Chronical Total occlusions). However, there is a problem in that the vibrations may be absorbed before reaching the distal end. In addition, using an external hand held vibrator interferes with the standard operation of the guidewire, and limits the operator from conveniently controlling the guidewire by manually holding its proximal end, again causing the need to deviate from the conventional practice workflow of the practitioner.
There thus exists a need for devices and techniques for treating occluded body internal passages, for characterizing the tissue/substance the treatment device is in contact with and determining its location within and about the body internal passage, and for safely opening occlusions therein without damaging the occluded internal passage.
It is therefore an object of the present invention to provide a method and device for opening occluded body internal passages and/or body organs.
It is another object of the present invention to provide a method and device for safely navigating treatment means, such as a catheter device, to a treatment site through body internal passages.
It is a further object of the present invention to provide a method and device for in vivo characterizing the tissue and/or substance being in contact with a treatment device.
It is yet another object of the present invention to provide a catheter device capable of inducing vibrations in a guidewire contained therein.
Other objects and advantages of the invention will become apparent as the description proceeds.